Whether it's being the victim, being the perpetrator, or having to watch this upsetting cycle of peer rejection and victimization, few adolescents are unaffected by bullying's harmful impact. This effect can last long past adolescence, as both being the bully and being the victim are linked to the development of both short- and long-term anxiety and depressive disorders. At some point during development, individuals begin to consider actions and behaviors that do not involve others being directly harmed to be morally wrong (e.g. homosexuality). In adults, this type of non-harm based moral condemnation is often underpaid by disgust, an emotion that has been linked to increased homophobic, sexist, and racist attitudes. However, when disgust begins to enter the moral toolbox and how it informs moral condemnation and social rejection within childhood and adolescence remains unknown. The goal of this project is to use an interdisciplinary approach to address this question, one that combines developmental, social cognitive and affective neuroscience. We will test a model that proposes that the relationship between disgust, moral condemnation, and social rejection is a learned one that reaches its peak during adolescence, a period marked by increased emotional reactivity and social hierarchical concerns. To test this model, we will use a converging methods approach that utilizes social-behavioral measures coupled with functional neuroimaging, across a wide developmental range (ages 6 to 25). In Study 1, we will examine how disgust sensitivity changes over time, and whether it is positively correlated with moral severity and reported peer rejection. In Study 2, we will use fMRI to look at the modulation of areas implicated in disgust by prefrontal regions linked to emotional regulation as individuals make socio-moral evaluations. We hypothesize that adolescents (as compared to children and adults) will be particularly impacted by disgust during socio-moral judgment, due to increased emotional reactivity coupled with relatively immature prefrontal regulatory regions. We further predict that, as disgust is a motivating emotion behind bullying behavior and the rejection of lower-status individuals, these behaviors will be more prevalent during adolescence. Both bullying and being bullied has been linked to long-term anxiety and depressive disorders, and adolescent victims of bullying behavior are at greater risk for committing suicide. Thus, gaining a better understanding of how moral condemnation and social rejection develops-and if the emotions that cause them can be successfully regulated-is of primary importance to curbing bullying behavior and its negative psychological and societal outcomes.